Conventionally, a copying machine is known which includes an automatic sheet feeding unit (or Auto-Document Feeder (ADF)) which successively feeds a plurality of originals to be copied, one at a time, from the original tray on to the original supporting plate.
In general, the automatic sheet feeding unit includes a sheet feeding section which picks up and feeds a plurality of originals one by one and a transportation section (transportation belt) which transports the picked-up original to the original supporting plate.
This automatic sheet feeding unit allows a user to make copies of a plurality of originals successively in response to a user's single instruction.
Also known is a copying machine which performs what we call a sheet through operation in which the original scanner (normally composed of an optical system) is not moved but fixed at a predetermined position below the original supporting plate and a single-sheet original, inserted through the original inserting port, is moved over the fixed original scanner. This sheet through operation is useful in copying a long-length original that is longer than the length of the original supporting plate in the original transportation direction.
However, the automatic sheet feeding unit described above can feed only an original shorter than the original supporting plate. It is therefore not practical to implement the sheet through operation in the conventional automatic sheet feeding unit. That is, conventionally, the successive automatic sheet feeding operation and the sheet through operation for a long-length original have been performed by separate mechanisms, and no copying machine has had these two mechanisms at the same time.
It is an object of the present invention to provide a copying machine that can perform both the successive automatic sheet feeding operation and the sheet through operation.
It is another object of the present invention to provide a mechanism structure and a control method suited for such a copying machine.